The invention relates to a device for attaching an element securely to a body, in particular fixing an element to a bone or joint in a minimally invasive manner.
In general, however, the device in accordance with the invention may also be used in open operations.
Operations using navigated instruments, i.e. instruments which are detected with respect to their spatial position, need the position of a body structure to be determined as precisely as possible for targeted surgery using the instrument, from which to determine, for example, the relative position with respect to the instrument. For this purpose, so-called reference systems have to be attached, as securely and torsion-proof as possible, to a body structure, such as for example a bone or similar structure. Similar problems arise for example in the targeted irradiation of body regions.
It is the object of the present invention to propose a device for attaching an element securely to a body, in particular to a bone, which in a simple manner is able to ensure a secure connection between element and body. In particular, a device is to be proposed which is suitable for fixing an element to a body in a minimally invasive manner.
This object is solved by the device having the features in claim 1. Advantageous embodiments are given by the sub-claims.
The device in accordance with the invention, for attaching an element securely to a body, in particular to a bone, comprises at least one movable holding element, by which the device may be tensed against the body. The holding element/s is/are preferably movable relative to the body, and in particular may be driven into or out of the body, in order to tense the element against the body itself or against structures over the body, such as for example muscles and/or skin over a bone, through this relative movement. The at least one holding element, movable relative to the body, can thus, when suitably adjusted and/or positioned, fix an element firmly connected to the device in accordance with the invention rigidly to the body, such as for example a bone, by tensing against the bone itself and/or against a tissue over the bone.
The device is preferably attachable to a connecting element fixed to or in the body, in particular attachable to such a connecting element anchored in the body. If, for example, a nail or screw is inserted into a bone, the device in accordance with the invention can be attached to or arranged on the distal area of the nail or screw. The device in accordance with the invention can particularly preferably be fixed to the connecting element arranged on or in the body, which may be achieved, for example, by an adhesive, positive locking or frictional connection. Once the device in accordance with the invention has been fixed to the connecting element arranged on or in the body, the device in accordance with the invention may preferably be tensed by the at least one movable holding element. For this purpose, one or more holding elements may be moved relative to the device in the direction of the body, such as for example the bone or a tissue structure over it, in order to place the device in a firm positional relationship, no longer movable relative to the body. In accordance with a preferred embodiment, the device in accordance with the invention is positioned on the one hand by being fixed to a connecting element arranged on or in the body, and on the other hand by being tensed or supported by the at least one holding element movable relative to the body.
Advantageously, at least two movable holding elements, in particular four or six movable holding elements, are provided, which may be moved either individually or in combination with other or all holding elements to fix and/or tense the device in accordance with the invention.
The holding elements are preferably formed as rod or needle-shaped elements, so-called spikes, which may be driven into or out of the device in accordance with the invention, individually or together. This embodiment is particularly advantageous if the device is to be fixed to a bone, as the device in accordance with the invention may be tensed and/or fixed to the bone itself by driving out said spikes and placing the proximal area and/or the tips of the spikes onto the bone or even penetrating into the bone.
In another preferred embodiment, a plane element, such as for example a plate or a flat conical element, is provided as the movable holding element and is particularly suited to being tensed against tissue structures, so for example being tensed against the skin. Tips or spikes protruding from the element may also be provided in this respect, for better fixing.
The device in accordance with the invention is preferably attached to the at least one connecting element arranged on or in the body by fastening a nut or screw, such that the device in accordance with the invention can be clamped to the connecting element fixed in the body by moving the screw, for example.
A nut or screw is preferably also provided for moving the at least one movable holding element, such that the at least one movable holding element may be driven into or out of the device via a movement of the screw, in order to tense the device against the body or to detach the device, respectively.
In general, however, it is also possible, instead of screws, to provide other mechanisms which enable fixing and/or fastening, such as for example a locking mechanism or a tensing mechanism held by springs.
The element arranged on the body using the device in accordance with the invention is preferably a reference star, which may comprise one or more, in particular three, passive and/or active markers, and preferably can be altered with respect to its spatial position by a tensing mechanism. It is, for example, advantageous to arrange the device in accordance with the invention such that the element arranged on it can still be moved, and for instance aligned with respect to cameras and fastened, after the device has been fixed. In this respect, it is particularly advantageous to enable the element to move about at least axes, wherein the element, such as for example the reference star, can preferably be fixed in its aligned position, for example by screws.
The invention further relates to a system for attaching an element securely to a body using a connecting element which may be inserted into or attached to the body, respectively, such as for example a screw which may be screwed into a bone, or a nail, and using the device described above, arranged on said element.
It is also possible in accordance with the invention to rigidly fix an element, such as for example a reference system, to the body in a minimally invasive manner using basic connecting elements commonly available on the market, such as for example Schantz screws, Kirschner wires, Steinmann nails, etc., or pedical screws which may be inserted into the spine, osteo-synthesis screws used in plates for bone fractures or also implants arranged on a body structure. Thus in accordance with the invention, a reference star for example can be attached torsion-proof to a body structure using a single element, such as for example a single screw. In general, however, it is also possible more than just one such element, or to use the device in operations which are not minimally invasive.
In the following, the invention will be described by way of two preferred example embodiments.